The invention concerns a collector for electrical machines.
A known collector of this type has a carrier bushing, on whose outer mantle swallowtail-type attachment devices which extend in the circumferential direction are provided. On this carrier bushing, collector segments are attached by means of complementary, swallowtail-type attachment devices. The collector segments each extend in an axial direction, and they form a rim of segments around the carrier bushing, with adjacent collector segments being electrically insulated from one another. The swallowtail-type attachment devices are designed in such a way that an intermediate space remains between the carrier bushing and the collector segments. This intermediate space is filled with a casting material, for example a fiber-reinforced epoxy resin. The casting material connects the collector segments with the carrier bushing, and, when hardened, forms an insulating layer between the carrier bushing and the collector segments.
In the known collector, the swallowtail-type attachment devices on the carrier bushing and the collector segments are selected in such a way that axially oriented collector segments can be attached to the carrier bushing radially from the outside. This is done by having swallowtails on the collector segments fit through the neck-type constrictions of swallowtail openings in the carrier bushing, and in the same manner, having swallowtails on the carrier bushing fit through the neck-type constrictions of swallowtail openings in the collector segments. When the rim of segments is installed, swallowtails do fit into swallowtail openings but the swallowtail structure does not mesh. A rigid connection between the carrier bushing and the rim of segments is not formed until the gap remaining between the two is filled with the casting material.
With this type of construction, it is true that axially oriented collector segments can be radially attached to the carrier bushing, but the casting material located between the segments and the carrier bushing is also under tensile stress during operation. For reasons of stability, the circumferential velocity of the known collector is therefore restricted to approximately 40 meters per second.
Modern drive technology, however, demands more revolutions per minute for many electrical machines, and also the possibility of operation at higher temperatures, in order to achieve greater output while maintaining the structural size, and to be able to eliminate intermediate gears in many cases. This requirement cannot be met with the known collector.
According to the not published German patent application No. P 34 43 107.1 of the applicant, the state of the art includes a collector of the stated type in which the attachment devices on the carrier bushing and the collector segments are resting in an intermeshing swallowtail arrangement when the collector segments are oriented axially, in which the neck of a swallowtail opening is so narrow that the head of the swallowtail which is fitted into it does not fit through. In order to achieve this intermeshing arrangement, the swallowtail crosspieces of the carrier bushing are interrupted by means of a radial slit. The collector segments are inserted into the slit and are pulled onto the carrier bushing in circumferential direction. After attaching all collector segments except one in this way, the slit is closed by means of a wedge which carries the last collector segment. The wedge is a profile part sitting in a profile groove of the carrier bushing, to take up the attacking centrifugal forces.
Although this collector construction is quite advantageous, it would require considerable manufacturing and installation expenditures. Furthermore and for reasons of stability, it is of disadvantage, on principle, that the swallowtail crosspieces of the carrier bushing are interrupted by a continuous radial slit.